Use pip config get to resolve the test index URL

Per asnare's review on #4803, the prior helper emulated pip's config-file
loading and assumed env vars (PIP_INDEX_URL, UV_INDEX_URL) that aren't set in
either dev or CI. Shell out to `pip config get global.index-url` instead and
fall back to public PyPI when no mirror is configured. After #4804 the JFrog
URL no longer carries credentials, so embedding it in the notebook fixture is
safe.

Co-authored-by: Isaac

Author: FastLee

tests/integration/source_code/test_libraries.py

@@ -3,10 +3,10 @@
 because it uses the context and the time it takes to run the test.
 """
 
-import configparser
 import logging
-import os
 import re
+import subprocess
+import sys
 import textwrap
 from pathlib import Path
 
@@ -17,22 +17,10 @@
 
 
 def _resolved_index_url() -> str:
-    """Return a pip-usable index URL for the current environment.
-
-    The notebook fixture invokes a real `pip install --index-url <url>`. CI's jfrog-auth action
-    writes a pip.conf at ``$PIP_CONFIG_FILE`` whose ``[global] index-url`` carries the
-    JFrog token; ``UV_INDEX_URL`` exists too but lacks credentials (uv stores auth in its keyring),
-    so passing it to pip would 401. Prefer ``PIP_CONFIG_FILE`` so pip can authenticate; fall back
-    to ``PIP_INDEX_URL`` and finally to the dev proxy used in local development.
-    """
-    pip_config_file = os.environ.get("PIP_CONFIG_FILE")
-    if pip_config_file and Path(pip_config_file).is_file():
-        parser = configparser.ConfigParser()
-        parser.read(pip_config_file)
-        url = parser.get("global", "index-url", fallback=None)
-        if url:
-            return url
-    return os.environ.get("PIP_INDEX_URL") or "https://pypi-proxy.dev.databricks.com/simple/"
+    """Return whichever pip mirror is configured locally, or public PyPI as a fallback."""
+    cmd = [sys.executable, "-m", "pip", "config", "get", "global.index-url"]
+    result = subprocess.run(cmd, capture_output=True, text=True, check=False, timeout=10)
+    return result.stdout.strip() if result.returncode == 0 else "https://pypi.python.org/simple"
 
 
 def _write_pytest_with_index_url_notebook(directory: Path) -> str: